He who of old spoke through symbols to Moses on Mount Sinai saying: “I am He Who Is,” was transfigured today upon Mount Tabor before the Disciples.
In His own person He showed them the nature of man arrayed in the original beauty of the Image.
Calling Moses and Elijah to be witnesses of this surpassing grace,
He made them partakers of the gladness,
foretelling His death on the Cross and His saving Resurrection.
(Great Vespers, Aposticha verse; italics mine)
The Transfiguration of Christ on the mountain clearly reveals to us that Jesus Christ is by nature God (see Matt. 17:1-9; Mk. 9:2-8; Lk. 9:28-36). He appeared in the glory of God with His face shining like the sun and His clothes glistening. The Father spoke from the bright, enveloping cloud: “This is My beloved Son. Hear Him!” As the Apostle John later wrote, “And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace truth” (Jn. 1:14). The Apostle Peter corroborates, “[W]e made known to you the power and coming of our Lord Jesus Christ, but were eyewitnesses of His majesty…we heard this voice which came from heaven when we were with Him on the holy mountain” (2 Pet. 1:16, 18).
The Son of God Jesus Christ is “the image of God” (2 Cor. 4:4; Col. 1:15), “the brightness of [God’s] glory and the express image of His person” (Heb. 1:3). In the great vision of the heavenly Jerusalem and home of the saints recorded by the Apostle John, “The city had no need of the sun or of the moon to shine in it, for the glory of God illuminated it. The Lamb (i.e., the Son of God who was slain and rose again) is its light” (Rev. 22:23). John the Baptist’s father Zachariah prophesied, “[T]he Dayspring from on high has visited us; to give light to those who sit in darkness” (Lk. 1:78, 79); and the Righteous Simeon reiterates, “For my eyes have seen Your salvation…a light to bring revelation to the Gentiles, and the glory of Your people Israel” (Lk. 2:30, 32).
The Transfiguration of Christ reveals the uncreated light emanating from its Source, the Son of God in the flesh Himself, or as Jesus described it just before the event, “the Son of Man coming in His kingdom…the kingdom of God present with power” (Matt. 16:28; Mk. 9:1; Lk. 9:27; see Dan. 7:9-14). The revelation of this uncreated light is for the benefit of Christ’s disciples, as the Lord states in His great prayer before His crucifixion. “And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was…And the glory which You have Me I have given them that believe in Me], that they may be one just as We are one…Father, I desire that they also whom You gave Me may be with Me where I am, that they may behold My glory which You have given Me; for You loved Me before the foundation of the world” (Jn. 17:5, 22, 24).
The uncreated light, glory, and kingdom of God are present in the Person of the God-man Jesus Christ, and He causes His disciples to participate in that kingdom for their life and salvation. As Christ preached and enacted His Kingdom through signs and wonders, so He sent His apostles to do the same (Matt. 10:7-8). Ultimately, when asked when the kingdom of God would come, Jesus answered: “Indeed, the kingdom of God is within you” (Lk. 17:21). Having just given the disciples His Body and Blood of the New Covenant (Lord’s Supper), Jesus taught, “I bestow upon you a kingdom, just as My Father bestowed one upon Me, that you may eat and drink at My table in My kingdom, and sit on thrones judging the twelve tribes of Israel” (Lk. 22:29-30). Therefore the Orthodox Liturgy in which we are gathered each Resurrection-Day (Sunday) always begins with these words: Blessed is the Kingdom of the Father, and of the Son, and of the Holy Spirit.
The verse above from Vespers confesses this awesome reality: In His own person He showed them the nature of man arrayed in the original beauty of the Image. The Transfiguration of Christ reveals the true nature of God-in-the-flesh, the Lord Jesus, AND it reveals what God has created and restored us human beings to be in Christ. As He shines with the uncreated light, we to are to participate and manifest that divine and glorious beauty. This transformation is accomplished through the crucifixion and resurrection of Christ and our personal conformity to that plan of salvation.
The Son of God is the Image (Gk., Icon), and we His people are images (icons) of the Image (cf. Col. 1:15 and Gen. 1:26-27). The Son of God is the Light of the world, and we His people are called to be the light of the world (cf. Jn. 8:12 and Matt. 5:14). The Son of God is the Sun of Righteousness, and we His people pursuing righteousness will shine forth as the sun in the kingdom of our Father (cf. Mal. 3:20 and Matt. 13:43). The Son of God is the morning star rising in the hearts of the faithful, and we the faithful are called to shine as stars in the world (cf. 2 Pet. 1:19 and Phil. 2:15).
The Apostle Paul exhorts: “And do not be conformed to this world, but be transformed (Gk., metamorphosis) by the renewing of your mind (Gk., nous; that is, spiritual faculty), that you may prove what is that good and acceptable and perfect will of God” (Rom. 12:2). “But we all, with unveiled face, beholding in a mirror the glory of the Lord, are being transformed into the same image form glory to glory, just as by the Spirit of the Lord” (2 Cor. 3:18).
Thus as with Moses and Elijah (who appeared with Christ on the mountain), as with Peter, James, and John (those of the 12 apostles most receptive to the vision), we too are to understand the Transfiguration of Christ as both the goal and means to achieve that goal of our lives with God. The goal is communion with God the Holy Trinity by participation in the uncreated light, glory, and kingdom of God. The means to achieve that goal is separation from the world of passions and sins to contemplate and practice the will of God in the heavenly places, which is done through repentance, faith, the love of God, and pure prayer devoid of earthly attachments.
By following Christ to the Cross and Resurrection, our transfiguration is possible. It is possible because of His Transfiguration for us and for our salvation.